1. Field of the Invention
The present invention generally relates to a rotating electric machine for a vehicle such as an automobile and a truck, more particularly relates to an alternating current (AC) generator for the vehicle.
2. Related Art
In a conventional rotating electric machine for a vehicle, each of permanent magnets is disposed between the circumferential side surfaces of adjacent two Lundell-type claw-like magnetic poles provided in a rotor, to diminish the magnetic flux leakage between the adjacent two claw-like magnetic poles. When the rotor rotates, centrifugal force is applied to the permanent magnets outside in a radial direction of the rotor. Therefore, it is necessary to prevent the permanent magnets from projecting to the radial outside of the rotor. Accordingly, the permanent magnets are fixed to the rotor by a magnet holder provided at the outer periphery of the permanent magnets. Specifically, the magnet holder is constructed with plural square cylindrical segments each of which is formed by pressing a non-magnetic material plate in a square cylindrical shape so as to cover each of the permanent magnets. Alternatively, as disclosed in U.S. Pat. No. 5,483,116, the magnet holder is made of a non-magnetic material, and is constructed with zigzag segments each having a U-shape. In this case, the permanent magnets are held by the segments having the U-shape.
However, the magnet holder is supported by the adjacent two claw-like magnetic poles only at radial outside ends thereof. Accordingly, when the rotor rotates, the centrifugal force is applied to the permanent magnets radially outside. Therefore, the magnet holder is deformed by the centrifugal force, and is readily broken. When the magnet holder is broken, the magnets may be separated from the rotor.